I've been running some tests with Server 2012 RTM Hyper-V and DSS7. Unfortunately whatever the alleged improvements for failover tolerance in Windows are, I'm still seeing blue screens on the guests when I initiate a failover.

Is the next release of v7 still on track to fix this issue in the second half of August??

Was the v7 update ever released? I just bought two new shiny Supermicro servers with Windows Server Datacenter 2012 and I want to play with Hyper-V!

10-24-2012, 07:47 PM

Gr-R

The changes have made it to a pre-release(beta) version of DSS V6.
DSS V7 changes are coming soon as well.

10-27-2012, 03:04 AM

techtou

Hi!
Can;t beleive what I am reading..
We've been using open-e DSS v6 with failover on at least four hyper-v cluster implementations.
Just upgraded to V7 on one of them and we have automatic failovers causing random BSODs on clustered VMs.
Is it true this is an issue in DSS V7 - I just went blue in the face trying to remotely trace where the cockup is only to read this alarming news.
Please enlighten me on which direction one should take here?
I loved your product/price/features so far. I would love to continue using it.
Thank you kindly for any insight.
Darko

10-30-2012, 05:26 PM

Tim Boothby

Quote:

Originally Posted by techtou

Hi!
Can;t beleive what I am reading..
We've been using open-e DSS v6 with failover on at least four hyper-v cluster implementations.
Just upgraded to V7 on one of them and we have automatic failovers causing random BSODs on clustered VMs.
Is it true this is an issue in DSS V7 - I just went blue in the face trying to remotely trace where the cockup is only to read this alarming news.
Please enlighten me on which direction one should take here?
I loved your product/price/features so far. I would love to continue using it.
Thank you kindly for any insight.
Darko

Hi Darko,

Are you saying that you could failover an ISCSI volume hosting a Hyper-V CSV from one DSS v6 box to another without problems? My experience is that this caused blue screens with v6, so nothing has changed on that front with the upgrade to v7.

Tim

11-02-2012, 09:05 PM

techtou

Hi Tim,
Yes, so far we've been successfully running VMs in hyper-v clusters which are stored on a iscsi lun in open-e DSS V6 SAN which is in active/passive failover with another open-e SAN. We have several implementations of this. Lun is a CSV for the hyper-v cluster and we use MPIO for two front-end cluster hosts with two iscsi switches, although it works fine with only one switch too. The failover works without VMs crashing - both failover and failback - it has been working for the past couple of years now. It was a bit of a trick to get this to work at first, but once configured right it ticks on just fine.
I am not sure if that has been a long standing issue with V6- I certainly don't remember seeing any posts where this has been confirmed - but we are only having problems with this since the upgrade to V7.

11-05-2012, 05:57 PM

techtou

Any news on the forthcoming patch?

11-07-2012, 05:26 PM

Tim Boothby

Quote:

Originally Posted by techtou

Hi Tim,
Yes, so far we've been successfully running VMs in hyper-v clusters which are stored on a iscsi lun in open-e DSS V6 SAN which is in active/passive failover with another open-e SAN. We have several implementations of this. Lun is a CSV for the hyper-v cluster and we use MPIO for two front-end cluster hosts with two iscsi switches, although it works fine with only one switch too. The failover works without VMs crashing - both failover and failback - it has been working for the past couple of years now. It was a bit of a trick to get this to work at first, but once configured right it ticks on just fine.
I am not sure if that has been a long standing issue with V6- I certainly don't remember seeing any posts where this has been confirmed - but we are only having problems with this since the upgrade to V7.

Ok - I'm interested to hear that. That's exactly the setup I have, 2 x DSS boxes as ISCSI backend for Hyper-V CSVs, cluster of 4 Hyper-V hosts, 2 switches, MPIO. Whenever I did a failover on the DSS boxes most of my Windows VMs would blue screen and my Linux VMs would end up with their file systems mounted read-only. I spent some time with Open-E support updating firmwares etc but could never get it working. Open-E eventually told me it was a known issue and failover with Hyper-V is not supported. I've had the same problem with DSS6 and DSS7, with Server 2008r2 and Server 2012.

There is a comment in the known issues section of the release notes "When using DSS V7 in windows 2008 cluster environment a failover event on DSS V7 will break i/o operation performed on the DSS V7 iSCSI target e.g. copying of files". This seems to down play the issue, in my experience it will crash most VMs, even if they are idling.

There are a couple of other threads about this here and here I've seen others with the same problem, but I think you are the first person to say this has worked! I wonder what was different about your setups?

I believe the issue is that a requirement for Hyper-V clustering is the storage supports ISCSI3 persistent reservations. DSS does, but these reservations are stored in memory and not replicated across to the cluster secondary so are lost during a failover.

I do believe a patch is on it's way, there was a beta of DSS6 a couple of months ago aimed at addressing this issue - although I didn't have much luck with this either.

Fingers crossed for a speedy fix.

Tim

11-09-2012, 06:06 PM

techtou

Hi!
Well, now you got me going..
I can tell you we have never tried this setup with more than two hyper-v cluster nodes so far.
I can tell you that cluster communication needs to be disallowed on iscsi networks, switches need to be connected to each other.
The iscsi initiator needs to be connected to one virtual ip with default settings, then when connecting the target use multipath option, use microsoft iscsi initiator as adapter, correct source and destination ips (as in the portal).
then you add session to already connected target using again microsoft iscsi adapter, the second initiator ip, and second destination ip.
This assumes you have two virtual ips configured on SANs.
Thats for the front end config, off the top of my head.

I think you are right on the money there with the cause - the reservations not replicating can cause BSOD or reset on VMs - all depending on what they were doing at the failover time. In the past two and a half years of using this we have had plenty of strange things happen, but have usually managed to pin them to some other part of the setup. We have also been updating the dss v6 fairly regularly. I, for the life of me, can't say what thing/action/upgrade stabilized this for us...
In any case, I too hope open-e can resolve this rather critical problem with a patch soon. I won't switch to VMWare anytime soon - but I might lose the SANs given what 2012 is capable of.